The Cable Center

This glossary of cable and telecommunications terms is intended to enhance your understanding of this dynamic industry. We are able to present this information with the generous help of CableLabs - consult their website for the most up-to-date information about cable technology.

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Mail Server
A computer responsible for processing and/or storing e-mail. It is the electronic equivalent of a post office. E-mail accounts exist on a mail server, where e-mail messages are stored until retrieval by the e-mail client.

Main Trunk
The major link from the headend to feeder lines.

Man-Machine Interface (MMI)
Another term for User Interface.

Management Information Base (MIB)
An SNMP-defined data structure used for storing and retrieving information to and from network elements.

Mandatory Ordinary Keycodes
The Mandatory Ordinary Keycodes are guaranteed to always be available to the application that has focus. The set of mandatory keycodes includes keycodes required by the MHP specification in the minimum platform capabilities section as the minimum set of input events.

Master Antenna Television (MATV)
Antenna and distribution system which serves multiple dwelling complexes such as hotels, motels and apartments.

Master Headend
A headend that collects television program material from various sources by satellite, microwave, fiber, and other means, and distributes this material to Distribution Hubs in the same metropolitan or regional area. A master headend MAY also perform the functions of a distribution hub for customers in its own immediate area.

Mean Time to Repair (MTTR)
In cable television systems, the MTTR is the average elapsed time from the moment a loss of radio frequency (RF) channel operation is detected up to the moment the RF channel operation is fully restored.

Media Access Control or Medium Access Control (MAC)
The MAC sublayer is the part of the data link layer that supports topology-dependent functions and uses the services of the Physical Layer to provide services to the Logical Link Control (LLC) sublayer. Or a component of a networking software stack. In the OSI 7-layer model, the Media Access Control is a part of layer 2, the data link layer.

Media Access Control Address (MAC-Address)
The unique hardware number assigned to network connection devices such as your computer’s network card. In Ethernet, it is written as a series of six pairs of characters divided by hyphens (e.g., 00-0F-3D-50-A1-98), and is also referred to as the hardware address or adapter address. Or the “built-in” hardware address of a device connected to a shared medium.

Media Access Control Procedure (MAC-Procedure)
In a subnetwork, that part of the protocol that governs access to the transmission medium independent of the physical characteristics of the medium, but taking into account the topological aspects of the subnetworks, in order to enable the data exchange between nodes. MAC procedures include framing, error protection, and acquiring the right to use the underlying transmission medium.

Media Access Control Service Access Point (MSAP)
The conceptual binding of a media access control (MAC) layer service provider to the protocol entities (i.e., data link layers) above it.

Media Access Control Sublayer (MAC-Sublayer)
The part of the datalink layer that supports topology dependent functions and uses the services of the physical layer to provide services to the logical link control (LLC) sublayer.

Media Gateway (MG)
A MG terminates switched circuit network (SCN) facilities (trunks, loops), packetizes the media stream, if it is not already packetized, and delivers packetized traffic to the packet network. It performs these functions in the reverse order for media streams flowing from the packet network to the SCN.

Media Gateway Control Protocol (MGCP)
Protocol follow-on to SGCP. Refer to IETF RFC 2705.

Media Gateway Controller (MGC)
An MGC is the overall controller function of the public switched telephone network (PSTN) gateway. It receives and mediates call-signaling information between the PacketCable™ and the PSTN domains, and it maintains and controls the overall call state for all calls.

MegaHertz (MHz)
One million cycles per second.

Message Authentication Code (MAC)
A fixed-length data item that is sent together with a message to ensure integrity, also known as a MIC.

Message Digest 5 (MD5)
A one-way hash algorithm that maps variable length plaintext into fixed-length (16 byte) ciphertext.

Message Integrity Check
A fixed-length data item that is sent together with a message to ensure integrity.

Message Transfer Agent (MTA)
A program responsible for receiving incoming messages and routing the messages to individual users.

Message Transfer Part (MTP)
The MTP is a set of two protocols (MTP 2, 3) within the signaling system number 7 (SS7) suite of protocols that are used to implement physical, data link, and network level transport facilities within an SS7 network.

MHP connected resource
An MHP connected resource is a resource used as part of the MHP which, on its own, does not conform to the specification but which is connected to an MHP terminal in such a way that the whole is part of the MHP.

MHP solution
The MHP solution encompasses the whole set of technologies necessary to implement the MHP including protocols and APIs.

MHP terminal
An MHP terminal is a single piece of physical equipment conforming to the MHP specification, in particular in that it contains a Virtual Machine and an instance of the MHP API.

Micro-reflections
Echoes in the forward or reverse transmission path due to impedance mismatches between the physical plant components. Micro-reflections are distinguished from discrete echos by having a time difference (between the main signal and the echo) on the order of 1 microsecond. Micro-reflections cause departures from ideal amplitude and phase characteristics for the transmission channel. These problems can be corrected by equalization.

Microsecond
One millionth of a second.

Microsoft Networking
The Microsoft standard for interconnecting Windows-based PCs on a LAN which uses the Client for Microsoft Networks.

Microwaves
High frequency radio waves used for telecommunications transmission. Line-of-sight, point-to-point transmission of signals at high frequency, usually above 890 MHz. Many cable television systems receive some television signals from a distant antenna location with the antenna and the system connected by microwave relay. Microwave frequencies require direct line-of-sight to operate. Trees and buildings distort or block the signal.

Microwave Oscillator
A device used to generate a microwave signal. It consists of two parts: a resonator to control the frequency of the microwave signal and an active device to generate the power.

Mid Band
The part of the frequency band that lies between television channels 6 and 7, received by the FCC for air, maritime and land mobile units, FM radio and aeronautical and maritime navigation. Mid-band frequencies, 108 to 174 MHz, can also be used to provide additional channels on cable television systems.

Mid Split
A frequency division scheme that allows bi-directional traffic on a single coaxial cable. Reverse channel signals propagate to the headend from 5 to 108 MHz. Forward path signals go from the headend from 162 MHz to the upper frequency limit. The duplex crossover band is located from 108 to 162 MHz.

Miles of Plant
The number of cable plant miles laid or strung by a cable system.

Mini-Slot
A mini-slot is an integer multiple of 6.25-microsecond increments.

Mixer
A non-linear circuit that produces an output at the sum and difference frequencies of an applied fixed or variable oscillator called the LO, and the FR input signal of interest.

Mode
The path a photon takes in going from one end of an optical fiber to another.

Modem
A data communications device. Modem is a combination of two words, modulate and demodulate. Strictly speaking, a modem is a device that accepts a digital signal, then converts or modulates it into an analog signal that another modem can convert back, or demodulate into digital form again. A modem’s speed and dependability are adversely affected by electro-magnetic interference, or static.

Modulation
When some characteristics of an electromagnetic wave are deliberately changed or manipulated for the purpose of transmitting information. Process by which signals are transformed to represent information (or data). Generally uses different frequencies to transmit data (FM). See also QAM.

Modulator
The electronic equipment required to combine video and audio signals from a studio and convert them to radio frequencies (RF) for distribution on a cable system. Also, a very low-powered television signal generator used to provide signals for distribution on a cable television system.

Monitor Application (MA)
The monitor application is a special unbound application with access to a privileged API set that manages the execution of all applications in the receiver.

Monitor Plus
A spot monitoring service provided by Nielsen which records both local broadcasts and national cable commercial activities.

Monomode
All photons take the same path down the center of the core of an optical fiber. Also Single-mode Fiber.

Mouse
A hardware pointing device used to control the movement of an on-screen cursor. The mouse buttons are then used to select items on the screen.

Moving Picture Experts Group (MPEG)
A voluntary body, which develops standards for digital, compressed moving pictures and associated audio.

MPEG-1
Video compression standard that requires a minimum of 30 frames per second with CD-quality sound (i.e. 16-bit stereo).

MPEG-2
An improved video compression standard over MPEG-1 that offers better resolution at the same 30 frames per second (as MPEG-1). Commonly used by cable television operators and direct broadcast satellite providers to offer digital video services because of its efficient use of capacity, improved quality over analog and stereo sound.

Multicast
A multicast is a message that is sent out to multiple devices on the network by a host.

Multi-Channel/Multi-Point Distribution (MMDS)
Private service utilizing a very high frequency (2 GHz) to transmit multiple television signals (also called wireless cable).

Multimedia Home Platform (MHP)
The Multimedia Home Platform consists of an MHP viewer terminal, including all possible low-to-high functionality implementations, its associated peripherals, and the in-home digital network.

Multimedia Terminal Adapter (MTA)
The device in a PacketCable network that connects the subscriber equipment (such as a telephone) to the network.

Multimode
When a photon careens off the optical fiber wall as it goes from one end to the other. Other photons take different paths. There are approximately 200 different paths in a single fiber.

Multi-path
Copies of the desired signal that have arrived at the antenna after bouncing from objects between the signal source and the antenna; these signals can either cancel or reinforce each other.

Multiple Dwelling Units (MDU)
Apartment buildings and condominiums.

Multiple (cable) Systems Operator (MSO)
A company that operates multiple cable systems.

Multiplexer
A device that allows several users to share a single circuit. It funnels different data streams into a single stream. At the other end of the communications link, another multiplexer reverses the process by splitting the data stream back into the original streams.

Multiplexing
The potential transmission of several feeds of the same cable network with the same programming available at different times of the day. This is seen as one possible use of the additional channel capacity that may be made available by digital compression. Multiplexing is also used by some cable networks to mean transmitting several slightly different versions of the network, for example several MTV channels carrying different genres of music.

Multipoint Access
User access in which more than one piece of terminal equipment is supported by a single network termination.

Multipoint Conferencing Unit (MCU)
A switching device that interconnects H.323- and T.120-compliant conferencing systems in a multipoint conference.

Multipoint Connection
A connection among more than two data network terminations.

Multipoint Controller (MC)
The H.323 entity that provides control of three or more endpoints in a multipoint conference.

Multipoint Microware Distribution System (MMDS)
A wireless broadband technology for Internet access.

Multipoint Mixing Controller (MMC)
A conferencing device for mixing media streams of multiple connections.

Multipurpose Internet Mail Extensions (MIME)
A specification for formatting non-ASCII data for transport over the Internet.

Must-Carry
The FCC rule requiring cable systems to carry all local broadcast television signals in their market.